The structures of higher fullerenes, i.e., those above C₇₀, are often hard to determine, as the species are only produced in small quantities and are often unstable. Derivatization, for example with chlorine, presents one avenue to stabilizing structures and allowing characterization of otherwise elusive isomers. Sergey Troyanov, Moscow State University, Russia, and collaborators at the University of Science and Technology of China were able to confirm the existence of C_s-C₈₂ isomer 4 (numbered according to P. W. Fowler and D. E. Manolopoulos) by chlorination and characterization of the derivative C₈₂Cl₂₀.

Chlorination of a mixture of C₈₂ and C₈₄ with VCl₄ in a glass ampoule for two months at 340 °C led to formation of small yellow crystals, which X-ray diffraction with synchrotron radiation revealed to be C₈₂Cl₂₀ with the carbon cage connectivity of C_s-C₈₂ (4). In the chlorinated derivative, only three chlorine atoms deviate from the mirror symmetry of the C_s cage, and the overall chlorination pattern is stabilized by the formation of aromatic substructures and isolated C=C bonds. Density functional calculations and comparison with the most stable C₈₂ isomer 3 ruled out the possibility of skeletal transformation induced by chlorination.

The authors comment that their results are a significant contribution to the chemistry of higher fullerenes.

• A New Isomer of Pristine Higher Fullerene C_s-C₈₂ (4) Captured by Chlorination as C₈₂Cl₂₀,
  Shangfeng Yang, Tao Wei, Sergey I. Troyanov,
  Chem. Asian J. 2012.
  DOI: 10.1002/asia.201201038
• An Atlas of Fullerenes,
  P. W. Fowler, D. E. Manolopoulos,
  Clarendon, Oxford, UK, 1995.
  ISBN: 978-0486453620

Also of interest:

• Identification for IPR Isomers of Fullerene C₈₂ by Theoretical ¹³C NMR Spectra Calculated by Density Functional Theory,
  Guangyu Sun and Miklos Kertesz,
  J. Phys. Chem. A 2001, 105, 5468–5472.
  DOI: 10.1021/jp004544z